Going Tidal, Need ???

Since you already have the OPPO 205 and use if for your DAC, you should just use it as a renderer for Roon and stream Tidal to it.  You don't need to buy any hardware.  Just use any computer and load Roon and Tidal on it and stream to the 205 using WIFI.

From the OPPO 205 webpage:

Built-in 802.11ac Wi-Fi or Gigabit Ethernet connects the UDP-205 to users’ home networks, so users can easily play media files stored on computers and home servers.

Roon is an incredibly rich and engaging way to browse and organize your music. It runs on most Mac, Windows, and Linux PCs, or on other products which include Roon Core. Being Roon Ready means that the UDP-205 transparently discovers and connects to Roon without any configuration, and bit-perfect audio is delivered from Roon to your UDP-205 player. Together, Roon and OPPO deliver the power, flexibility, and performance of networked audio, with the easiest setup and highest reliability available. The UDP-205 supports streaming stereo PCM audio up to 192 kHz 24-bit from Roon. Learn more about Roon Ready, and sign up for a free 60-day trial by redeeming the code 0PP0-M1NA-MLB4.

You even can maybe get a 60-day free trial of Roon.

Steve N.

Empirical Audio

As for hi-rez, this is another story. The best hi-rez you will get with either a quality USB converter or a quality Ethernet renderer. Either of these will reside between the computer and your DAC (OPPO205). This converter should provide a very low jitter digital output. The reason for using an external converter is to avoid using the high-jitter master clock inside the OPPO. Instead, the low jitter master clock in these external converters is used.

This converter will connect to your computer where your hi-rez files reside using USB, Ethernet or WIFI. The output of the converter to the DAC will usually be a high-quality digital coax (S/PDIF) cable. This cable should be a BNC-BNC with RCA adapters and not shorter than 4 feet or 1.25m.

For playback, you can use a myriad of different software on your computer. I personally use Linn Kinsky and Minimserver for my Ethernet renderer because the SQ is unbeaten. Both freeware and available for Mac or PC.

Here is an example of a low jitter renderer:

https://www.audiocircle.com/index.php?topic=156409.0

Steve N.

Empirical Audio

"The Roon software is supposed to make the operation easier?"

Roon is one of many playback apps you can use. Most of them are easy, although some prefer Roon. Many use Linn Kazoo and Lumin.

"My goal is to obtain the best sound available via steaming."

I would start with the Oppo and get it working with Roon and Tidal on a PC or Mac and then go from there.

If you want better SQ later, then you can go several directions:

1) add an Ethernet renderer and drive the Oppo with S/PDIF cable - $2-4K These can support Roon or DLNA.

2) replace the Oppo with another USB DAC and use USB from the computer to DAC - $2-4K

3) replace the Oppo with another DAC and add a USB converter to drive the DAC.  The USB converter connects with USB to the computer. - $4-6K

4) replace the Oppo with another DAC and use Ethernet renderer to drive the DAC You can get renderers that work with Roon or DLNA. $4-6K

If you want to stream free tracks from Amazon Prime, then you will need to do #2 or #3.

"Ethernet connection better than WiFi I would assume?"

Not necessarily. Depends on the hardware. If you can reach your stereo rack from your router or switch with a reasonable length Ethernet cable, then definitely go wired Ethernet

In general, it is easier to get Ethernet to sound great than USB. Less hoops to jump through. You will need high-performance expensive cables in either case to get the best SQ.  I use Ethernet myself with a DLNA renderer that delivers 10psec of jitter over a S/PDIF cable to a DAC.

Steve N.
Empirical Audio